Question

Which of the following processes have a ΔS > 0? Which of the following processes have a > 0? 2HCl(g) → H2(g) + Cl2(l) cesium chloride dissolves in pure water lithium fluoride forms from its elements 2NH3(g) + CO2(g) → NH2CONH2(aq) + H2O(l) All of the above processes have a ΔS > 0.

Answer 1

Answer:  b)  cesium chloride dissolves in pure water

Explanation:

Entropy is the measure of randomness or disorder of a system. If a system moves from  an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

$\Delta S$ is positive when randomness increases and $\Delta S$ is negative when randomness decreases.

a) $2HCl(g)\rightarrow H_2(g)+Cl_2(l)$

As one mole of the gas is converted to liquid, the randomness of particles decreases and hence  $\Delta S$ is negative and $\Delta S<0$.

b)  cesium chloride dissolves in pure water:

As solid is converted to aqueous state and ions are formed, the randomness of particles increases and hence  $\Delta S$ is positive and $\Delta S>0$

c) lithium fluoride forms from its elements :

As molecules combine to form a single product, the randomness of particles decreases and hence  $\Delta S$ is negative and $\Delta S<0$

d) $2NH_3(g)+CO_2(g)\rightarrow NH_2CONH_2(aq)+H_2O(l)$

As gas is converted to liquid, the randomness of particles decreases and hence  $\Delta S$ is negative and $\Delta S<0$